The present invention relates to an inspection of conductive patterns formed on a circuit board.
In manufacturing processes of a circuit board, after forming electrically conductive patterns on a board, it is required to inspect the presence of disconnection and/or short-circuit in the conductive patterns.
As for such an inspection technique, a contact type inspection technique has been heretofore known in which a conductive pattern was subjected to a continuity check or the like by bringing two separate pins into contact with the opposite ends of the conductive pattern to apply an electric signal from one of the two pins to the conductive pattern and then receive the electric signal through the other pin.
However, recent progressive densification in the conductive patterns makes it difficult to bring the pins into contact with each of the conductive patterns from point to point precisely. Thus, a non-contact type inspection method has been proposed in which no pin was used at the receiving side and the electric signal was received without contacting the conductive pattern.
In this non-contact type inspection technique, a pin to be contacted to the conductive pattern is placed at one end of the conductive pattern, and a sensor is placed adjacent to the other end of the conductive pattern in a non-contact manner. Then, an electric signal having temporal variations is supplied to the pin, and a corresponding electric signal which appears at the sensor after passing through the capacitance lying between the conductive pattern and the sensor is detected to inspect the disconnection and others of the conductive pattern.
According to this technique, the inspection can be adequately performed by bringing the pin into contact with only one end of the conductive pattern. Thus, this technique is advantageous particularly to the inspection of microscopic conductive patterns.
However, the conventional non-contact type inspection technique is required to bring the pin into contact with one end of the conductive pattern and thereby the inspection cannot be carried out in a complete non-contact manner. Thus, considering recent further progressive densification in the conductive patterns, such a conventional technique can be limited in the scope of applications. In addition, it is required to provide a pad for bringing the pin into contact therewith at one end of the conductive pattern. Providing such an originally unnecessary pad runs counter to enhancing packaging density.
It is therefore an object of the present invention to provide an inspection apparatus, an inspection method and an inspection unit therefor capable of inspecting conductive patterns in a complete non-contact manner.
According to one aspect of the present invention, there is provided an inspection apparatus for inspecting a conductive pattern of a circuit board in a non-contact manner, comprising a plurality of conductive cells arranged with leaving a space therebetween, supply means for supplying an inspection signal having temporal variations to at least one of the cells, processing means for processing an output signal appearing at another at least one of the cells, switching means for allowing each of the cells to be connected individually with either one of the supply means and the processing means, and control means for controlling the switching means.
In this aspect of the present invention, the inspected conductive pattern and the cells will be capacitively coupled to each other by placing the cells close to the conductive pattern. Thus, once the inspection signal is supplied to one of the cells, a signal appears at the conductive pattern in response to the inspection signal, and thereby a signal (output signal) appears at another ones of the cells.
Then, connecting each of the cells with either one of the supply means and the processing means by the switching means allows the conductive pattern to be inspected in a complete non-contact manner without using any pins.
According another aspect of the present invention, there is provided an inspecting unit for inspecting a conductive pattern of a circuit board in a non-contact manner, comprising a plurality of conductive cells arranged with leaving a space therebetween, an input terminal receiving an inspection signal to be supplied to at least one of the cells, an output terminal for outputting a signal from another at least one of the cells, a control terminal receiving a control signal for selecting a specific cell from the cells, and switching means for allowing each of the sells to be connected individually with either one of the input terminal and the output terminal based on the control signal.
In this aspect of the present invention, the inspected conductive pattern and the cells will be capacitively coupled to each other by placing the cells close to the conductive pattern. Thus, once the inspection signal is supplied to one of the cells, a signal appears at the conductive pattern in response to the inspection signal, and thereby a signal (output signal) appears at another ones of the cells.
Then, connecting each of the cells with either one of the input terminal and the output terminal by the switching means allows the conductive pattern to be inspected in a complete non-contact manner without using any pins.
According still another aspect of the present invention, there is provided an inspection method for inspecting an conductive pattern of a circuit board in a non-contact manner, comprising the steps of placing a plurality of conductive cells along the conductive pattern with leaving a space therebetween, supplying an inspection signal having temporal variations to at least one of the cells, detecting an output signal appearing at another one of the cells through the conductive pattern in response to the applied inspection signal, and inspecting the conductive pattern based on the detected output signal.
In this aspect of the present invention, the inspected conductive pattern and the cells will be capacitively coupled to each other by placing the cells along the conductive pattern. Thus, the inspection signal can be supplied to the conductive pattern by supplying the inspection signal to the one of the cells. Further, a signal appears at the conductive pattern in response to the inspection signal, and thereby a signal (output signal) appears at another one of the cells. By detecting this signal, the conductive pattern can be inspected. This allows the conductive pattern to be inspected in a complete non-contact manner without using any pins.